Re: [PATCH v5 0/2] i2c: add DMA support for freescale i2c driver

[Marek Vasut]

On Thursday, July 24, 2014 at 05:36:34 AM, Yao Yuan wrote:
> Hi,
> 
> Marek Vasut wrote:
> > On Wednesday, July 23, 2014 at 10:24:41 AM, Yuan Yao wrote:
> > > Changed in v5:
> > > - add "*chan_dev = dma->chan_using->device->dev" for reduce the call
> > > time.
> > 
> > Did you check if the compiler generates different code ?
> 
> Sorry, I didn't compare the assembly code. It's a subtle change.
> As you mentioned the "noodle" before.
> 
> Old:
> dma_map_single(dma->chan_using->device->dev, ...);
> dma_mapping_error(dma->chan_using->device->dev, ...);
> dma_unmap_single(dma->chan_using->device->dev, ...);
> 
> New:
> struct device *chan_dev = dma->chan_using->device->dev;
> dma_map_single(chan_dev, ...);
> dma_mapping_error(chan_dev, ...);
> dma_unmap_single(chan_dev, ...);

You should not use optimization and code cleanup interchangably. Thanks for 
clarifying what this is.

Best regards,
Marek Vasut
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/